As long as the toolset isn't release i don't think theres much of a hurry, i guess.

So in the meantime already went through the game directory. It's pretty cool!

Most physics settings are xml cfg files that can be easily edited using any text editor.
Number of autosaves, Field of View, movement speed, damage values, oil lamp behavior are just a few minor examples of things that can be edited within seconds and instantly take effect after starting the game.

'Trivial' resources include textures (.jpg and .dds formats) and audio (.ogg files), both of which are referenced in cleartext in the xml description files of (for example) game entities or events like flashbacks.

A lot of the fancy graphics effects are done in glsl, which is a human readable shader code format. I've tried a few minor edits (going through the debug modes, testing the rightfully discarded relief mapping) and all of them are effective instantly after starting the game.

All of that probably isn't relevant or practical for real mods since it affects the base game and modifying more complex stuff manually is too tedious and error-prone, but hey, if you want to play with a bright pink lantern that slurps up oil twice as fast or absolutely irrationally hate the reduced 60% movement speed during flashbacks but want double the blur you could easily adjust that.

If possible, I want to mod in a weapon. I know it's contrary to the theme of the game, but once I get done with a playthrough, I think an unlockable perk would be a nice way to increase replayability. Maybe a voice-thrower for one replay (to make monsters go away), a knife after two, and a gun after three?